405 SRDT A/C wiring diagram
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  1. #1
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    Default 405 SRDT A/C wiring diagram

    Hi guys,
    Does anyone have a wiring diagram for a 94 405 srdt? I had an A/C /Auto electrician guy looking at my car today because my A/C cuts in and out. I thought my gas was getting low but it tested fine. He said it has to be the relay but I dont know where it is and neither did he. Has anyone had this problem before or know where the relay is? He also checked the temperature sensor and that was fine. If anyone has a diagram, I'd really appreciate it! Thanks

    lamlam

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  2. #2
    Fellow Frogger! Monsieur 405's Avatar
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    Air con or fan?

    Monsieur 405

  3. #3
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    It's the A/C. The fan works well. I have the haynes manual for the petrol version 405 but its no help at all. Have you had this problem before?

  4. #4
    Fellow Frogger! stew's Avatar
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    Most faults with that A/C are from poor solder joints in the control unit. Pull both sides off the lower part of the centre console. The unit is a black box right on the very front top part of the tunnel. Ignition on, ac on and slide the temp slide to hot. Reach under and touch the box. While doing that, slide the temp to cold. In 3 seconds the box should click. That is the compressor relay. The compressor should click and both radiator fans should go to low speed.
    If the box does not click, wiggle the harness plug gently and the thing will probably click for you. If so pull the box out ( good luck), 8mm bolts hold it to the tunnel. Dismantle board out and resolder the relay. Sparky can do that!
    Another common fault is the junky A/C switch itself. If it feels squishy and not positive that needs to be over ridden and another switch fitted. I use another demist button. Sparky work.
    Tell us if you think, what they did to fit that computer box where they did, was clever French engineering.

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    Fellow Frogger! Monsieur 405's Avatar
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    My fan is a tad dicky at the moment, and the air con has packed up completely... However, I think I have a spare air con console somewhere... I'll have a check. It definitely works...

    As for the 'Haynes book of Mystery'... It's trickier to decipher than a David Astle cryptic crossword!

    Monsieur 405

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    Stew,
    Thanks very much for the info, your spot on. Yesterday I did what you said and used my magic hoodini skills to remove that A/C relay. Im lucky enough to have spares of everything so I removed a different a/c relay and plugged it in and it worked right away. Only until I screwed it back in place and went for a test drive, lol. then it failed again. When i plugged in that new relay, the a/c compressor kicked on when the temp was hot or cold and the fan speed was low or high. As soon as I pressed the a/c button, it kicked on. I am thinking that is what it is suppossed to do. When I went on the test drive, the compressor was kicking on and off a lot and eventually didnt kick on at all. I am going to have another go at it today and make sure the relay is connected firmly. If thats not it, Im searching for something else.

    Thanks for the info!

    lamlam

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    Stew,
    I did the test you were talking about. I held the relay and moved the temp guage from hot to cold and after a few seconds, it clicked every time. All with just the ignition on, not the engine. The question is, what would cause the relay to turn off? Is it the temp sensor thats sending faulty readings? Do you know what the temp sensor looks like and where it is? Something is telling my relay to turn off and I would like to rectify that!
    Thanks for all your help!

    lamlam

  8. #8
    Fellow Frogger! stew's Avatar
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    If the relay is clicking that bit is OK. Now, here is the next test! Behind the passenger headlight is another black box. It is the fan controller and compressor cut out for high temp. It gets, you guessed it, covered in water and schmidt. With every thing on( not engine running, though, wiggle and work the plug there. Also there is a high pressure switch on the receiver dryer. It gets ignition to one pin, power from the box and then it switches comp on if pressures are good and will turn fans on high via the box. If you bridge the switch with power to either terminal one wire should turn on the compressor. That confirms the wire from box to comp. is good.

  9. #9
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    Ok,
    I found the box. What exactly am I testing for? To see if it clicks too or to see how dirty it is in the plug? Im lucky enough to have spare parts, So i'll replace that relay and make sure all the connections are clean and see if that solves the problem.

  10. #10
    Fellow Frogger! stew's Avatar
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    Same thing, wiggle test and check for corrosion in plug. I have had to refit the harness plg before. Whack in another box and see!

  11. #11
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    Default Stew

    I wacked another box in but the results were the same! As soon as I put the a/c on low, the relay clicks and turns the compressor off and then it wont click on again. If I have the ac on full blast, it works and stays cold. If its half way, it works for 5 mins and then shuts off! Seems like all the things Ive checked so far are fine, whats next??

  12. #12
    Fellow Frogger! stew's Avatar
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    So the comp. cycles with the thermostat setting and won't come back on? That is almost always the box under the dash. The relay heats up and the solder joints won't carry the current again. You can pull that apart and see the relay. Plug it back in and wait for it to cycle. When it doesn't come back on press the relay contact and see if she works! You may find it hot!
    Move the board gently and it may just give up the secret!

  13. #13
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    Default Symptoms

    So, here are the symptoms :

    When the A/C is on low, the relay inside the car wont click on.
    When the A/C is on medium, the relay kicks on and turns off again in 5 mins or so.
    When the A/C is on high, the relay stays on and so does the compressor.

    So that eliminates everything in the engine compartment doesnt it? The box behind the headlight and the compressor are doing what they are told. What is it that tells the relay what to do? There has to be an in cabin temperature sensor under the dash somewhere that could be having an effect.
    Perhaps when the A/C is on full blast, it is sending more current to the relay which is keeping it on? Dont forget that I have replaced that relay and I have a few other relays sitting around here that all work. (as far as I know) They all seem to be reacting the same way and turning on and off at the same times. There must be something else causing them to act that way. What about burnt wiring in there somewhere on the way to the relay?

    This is definitely a puzzle I hope to solve! Thanks for your help stew!

    lamlam

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    Fellow Frogger! stew's Avatar
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    Just got in! I'll have a think over weekend and we might just find what's what, hey?

  15. #15
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    Default The heat sensor

    samples the air drawn in through the little slots above the glovebox the fan that draws the air in is located above the glove box S1[S2 HAS LITTLE VENT TO THE RIGHT OF THE GLOVEBOX ,I HAVNT HAD THIS DASH APART SO NOT SURE ON THE FAN ,maybe the fans intermitent and giving false readings to the relay box ,seems like a dodgy connection somewhere if it only drops out when the car is moveing ,theres a pressure switch on the air con filter i think that shuts the system down if gas level /presure is low ,could be a bad connection there make sure the wire going onto the compreser isnt rubbing on the pulley ,it runs real close .PUGS

  16. #16
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    So what is happening is one of a few things. Either the control unit is not getting signal from the panel on low or the unit is not reading it. remove the circuit board from the box and fit it up to the plug. Run the air with the panel set on mid way. Once the compressor clicks in gently bend and twist the board. It might just drop the comp. out.

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